1. Field of the Invention
This invention relates generally to well cementing devices and, specifically to a wireline conveyed cement retainer which allows circulation of well fluids through the interior of the retainer while running-in to the desired depth in the well bore.
2. Description of the Prior Art
A cement retainer is a tubular member having external gripping and sealing means which can be set within a well bore to seal and grip the surrounding well bore or casing. The retainer is typically provided with a valve which can be used to open and close off cementing ports. The retainer is run on either a wireline or on a tubing string, and the gripping and sealing members can be actuated to seal off an annular space within the well bore between the cement retainer and the surrounding casing. After setting the retainer on a wireline setting tool, the setting tool is removed and a tubing string is lowered into position and inserted within the bore of the set retainer. In a "squeeze cementing" job, cement is then pumped through the tubing string, through the interior of the retainer, and out the cementing ports to seal off perforations in the casing. The retainer valve is then closed to close off the cementing ports and retain the cement below the retainer.
In the prior art devices, it was not generally possible to circulate well fluids through the interior of the retainer as it was being lowered on a wireline to the desired location within the well bore. Because any fluid within the well was required to pass about the exterior of the retainer, and therefore between the gripping and sealing members and the surrounding casing, the retainer tended to "float" while being lowered. This tended to slow the running-in operation and added to the rig time required to set the retainer at the desired location.
The present invention has as its object the provision of a wireline set cement retainer which allows circulation through the interior of the retainer while running the retainer to the desired location within the well bore.
Another object of the present invention is the provision of a simple and reliable release mechanism for releasing the wireline setting tool from the cement retainer after setting the retainer at the desired location within the well bore.